Lightweight polymer ammunition cartridge casings

ABSTRACT

One embodiment of the present invention provides a polymeric ammunition cartridge and methods of making and using the same. The cartridge includes a substantially cylindrical insert connected to a substantially cylindrical polymeric middle body. The substantially cylindrical insert includes a top surface opposite a bottom surface and a substantially cylindrical coupling element that extends from the bottom surface, a primer recess in the top surface that extends toward the bottom surface, a primer flash hole positioned in the primer recess to extend through the bottom surface, and a flange that extends circumferentially about an outer edge of the top surface. The substantially cylindrical polymeric middle body includes a substantially cylindrical polymeric bullet-end and a substantially cylindrical polymeric coupling end connected by a powder chamber, wherein the substantially cylindrical polymeric coupling end extends over the substantially cylindrical coupling element and covers a circumferential surface of the primer flash hole.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional Application of U.S. patent applicationSer. No. 16/420,661 filed May 23, 2019, which is a ContinuationApplication of U.S. patent application Ser. No. 14/320,961 filed on Jul.1, 2014 now U.S. Pat. No. 10,352,670, which is a Continuation-in-Partapplication of U.S. patent application Ser. No. 14/011,202 filed on Aug.27, 2013 now U.S. Pat. No. 9,546,849, which is a Divisional Applicationof U.S. patent application Ser. No. 13/292,843 filed on Nov. 9, 2011 nowU.S. Pat. No. 8,561,543, which claims the benefit of U.S. ProvisionalPatent Application Ser. No. 61/456,664, filed Nov. 10, 2010, thecontents of each are hereby incorporated by reference in their entirety.

TECHNICAL FIELD OF THE INVENTION

The present invention relates in general to the field of ammunition,specifically to compositions of matter and methods of making and usingsubstantially cylindrical inserts made by metal injection molding.

STATEMENT OF FEDERALLY FUNDED RESEARCH

None.

INCORPORATION-BY-REFERENCE OF MATERIALS FILED ON COMPACT DISC

None.

BACKGROUND OF THE INVENTION

Without limiting the scope of the invention, its background is describedin connection with lightweight polymer cartridge casing ammunition.Conventional ammunition cartridge casings for rifles and machine guns,as well as larger caliber weapons, are made from brass, which is heavy,expensive, and potentially hazardous. There exists a need for anaffordable lighter weight replacement for brass ammunition cartridgecases that can increase mission performance and operationalcapabilities. Lightweight polymer cartridge casing ammunition must meetthe reliability and performance standards of existing fielded ammunitionand be interchangeable with brass cartridge casing ammunition inexisting weaponry. Reliable cartridge casings manufacturing requiresuniformity (e.g., bullet seating, bullet-to-casing fit, casing strength,etc.) from one cartridge to the next in order to obtain consistentpressures within the casing during firing prior to bullet and casingseparation to create uniformed ballistic performance. Plastic cartridgecasings have been known for many years but have failed to providesatisfactory ammunition that could be produced in commercial quantitieswith sufficient safety, ballistic, handling characteristics, and survivephysical and natural conditions to which it will be exposed during theammunition's intended life cycle; however, these characteristics havenot been achieved.

For example, U.S. patent application Ser. No. 11/160,682 discloses abase for a cartridge casing body for an ammunition article, the basehaving an ignition device; an attachment device at one end thereof, theattachment device being adapted to the base to a cartridge casing body;wherein the base is made from plastic, ceramic, or a composite material.

U.S. Pat. No. 7,610,858 discloses an ammunition cartridge assembled froma substantially cylindrical polymeric cartridge casing body defining acasing headspace with an open projectile-end and an end opposing theprojectile-end, wherein the casing body has a substantially cylindricalinjection molded polymeric bullet-end component with opposing first andsecond ends, the first end of which is the projectile-end of the casingbody and the second end has a male or female coupling element; and acylindrical polymeric middle body component with opposing first andsecond ends, wherein the first end has a coupling element that is a matefor the projectile-end coupling element and joins the first end of themiddle body component to the second end of the bullet-end component, andthe second end is the end of the casing body opposite the projectile endand has a male or female coupling element; and a cylindrical cartridgecasing head-end component with an essentially closed base end with aprimer hole opposite an open end with a coupling element that is a matefor the coupling element on the second end of the middle body and joinsthe second end of the middle body component to the open end of thehead-end component; wherein the middle body component is formed from amaterial more ductile than the material head-end component is formedfrom but equal or less ductile than the material the bullet-endcomponent is formed from. Methods for assembling ammunition cartridgesand ammunition cartridges having the headspace length larger than thecorresponding headspace length of the chamber of the intended weaponmeasured at the same basic diameter for the cartridge casing withoutbeing so large as to jam the weapon or otherwise interfere with itsaction are also disclosed.

Shortcomings of the known methods of producing plastic or substantiallyplastic ammunition include the possibility of the projectile beingpushed into the cartridge casing, the bullet pull being too light suchthat the bullet can fall out, the bullet pull being too insufficient tocreate sufficient chamber pressure, the bullet pull not being uniformfrom round to round, and portions of the cartridge casing breaking offupon firing causing the weapon to jam or damage or danger whensubsequent rounds are fired or when the casing portions themselvesbecome projectiles. To overcome the above shortcomings, improvements incartridge case design and performance polymer materials are needed.

BRIEF SUMMARY OF THE INVENTION

One embodiment of the present invention provides a method of making asubstantially cylindrical insert by metal injection molding comprisingthe steps of: providing a mold of the substantially cylindrical insertto form a substantially cylindrical insert mold; providing a feedstockcomprising a powdered metal and a first binding agent and a secondbinding agent; injection molding the feedstock into the substantiallycylindrical insert mold to form an substantially cylindrical inserthaving a first size; debinding the substantially cylindrical insert toremove the first binding agent; and sintering the substantiallycylindrical insert to remove the second binding agent and form afinished substantially cylindrical insert having a second size. Thesubstantially cylindrical insert comprising a top surface opposite abottom surface and a substantially cylindrical coupling element thatextends from the bottom surface, a primer recess in the top surface thatextends toward the bottom surface, a primer flash hole positioned in theprimer recess to extend through the bottom surface, and a flange thatextends circumferentially about an outer edge of the top surface. Thepowdered metal comprises stainless steel.

One embodiment of the present invention provides an ammunition cartridgecomprising: a substantially cylindrical insert made by the processcomprising providing a mold of the substantially cylindrical insert toform a substantially cylindrical insert mold; providing a feedstockcomprising a powdered metal and a first binding agent and a secondbinding agent; injection molding the feedstock into the substantiallycylindrical insert mold to form an substantially cylindrical inserthaving a first size; debinding the substantially cylindrical insert toremove the first binding agent; and sintering the substantiallycylindrical insert to remove the second binding agent and form afinished substantially cylindrical insert having a second size; andbonded to a substantially cylindrical polymeric middle body comprising asubstantially cylindrical polymeric bullet-end and a substantiallycylindrical polymeric coupling end connected by a powder chamber,wherein the substantially cylindrical polymeric coupling end extendsover the substantially cylindrical coupling element and covers ancircumferential surface of the primer flash hole.

The substantially cylindrical polymeric middle body may include a nylonpolymer. The substantially cylindrical insert may include adhesivelyfitted to the substantially cylindrical polymeric middle body. Thesubstantially cylindrical insert may be adhesively fitted to thesubstantially cylindrical polymeric middle body with a curable polymeradhesive. The substantially cylindrical insert, the substantiallycylindrical polymeric middle body or both may include a coating toadjust the shrinkage.

One embodiment of the present invention includes a substantiallycylindrical insert mold for making a substantially cylindrical insert bymetal injection molding comprising: a top surface opposite a bottomsurface and a substantially cylindrical coupling element that extendsfrom the bottom surface; a primer recess in the top surface that extendstoward the bottom surface; a primer flash hole positioned in the primerrecess to extend through the bottom surface; and a flange that extendscircumferentially about an outer edge of the top surface.

One embodiment of the present invention provides a polymeric ammunitioncartridge. The cartridge includes a substantially cylindrical insertconnected to a substantially cylindrical polymeric middle body. Thesubstantially cylindrical insert includes a top surface opposite abottom surface and a substantially cylindrical coupling element thatextends from the bottom surface, a primer recess in the top surface thatextends toward the bottom surface, a primer flash hole positioned in theprimer recess to extend through the bottom surface, and a flange thatextends circumferentially about an outer edge of the top surface. Thesubstantially cylindrical polymeric middle body includes a substantiallycylindrical polymeric bullet-end and a substantially cylindricalpolymeric coupling end connected by a powder chamber, wherein thesubstantially cylindrical polymeric coupling end extends over thesubstantially cylindrical coupling element and covers a circumferentialsurface of the primer flash hole. Other embodiments include the primerinserted into the primer recess, the charge located in the powderchamber, and/or a bullet or projectile.

One embodiment of the present invention provides a method of making anammunition cartridge comprising: providing a metal injection moldedsubstantially cylindrical insert made by providing a mold of thesubstantially cylindrical insert to form a substantially cylindricalinsert mold; providing a feedstock comprising a powdered metal and afirst binding agent and a second binding agent; injection molding thefeedstock into the substantially cylindrical insert mold to form ansubstantially cylindrical insert having a first size; debinding thesubstantially cylindrical insert to remove the first binding agent; andsintering the substantially cylindrical insert to remove the secondbinding agent and form a finished substantially cylindrical inserthaving a second size; providing a substantially cylindrical polymericmiddle body comprising a substantially cylindrical polymeric bullet-endand a substantially cylindrical polymeric coupling end connected by apowder chamber, and bonding the substantially cylindrical polymericcoupling end to the metal injection molded substantially cylindricalinsert to form a bonded ammunition cartridge; and curing the bondedammunition cartridge. In addition the present invention provides thefurther step of applying a coating to adjust the shrinkage to thesubstantially cylindrical insert, the substantially cylindricalpolymeric middle body or both.

In one embodiment the substantially cylindrical polymeric middle body isformed from a ductile polymer, more preferably a nylon polymer. In oneembodiment the substantially cylindrical polymeric middle body is formedfrom a fiber-reinforced polymeric composite. In one embodiment thefiber-reinforced polymeric composite contains between about 10 and about70 weight percent glass fiber fillers, mineral fillers, or mixturesthereof. In one embodiment the substantially cylindrical polymericbullet-end and bullet are further welded or bonded together.

The substantially cylindrical polymeric bullet-end may include a forwardopening end having a first and a second mechanical interlock forengagement between the forward opening end and a bullet. In oneembodiment the forward opening end includes two or more canneluresformed on an outer circumferential surface of the forward opening end.In one embodiment the forward opening end comprises one, two or moreannular rings that mate with one, two or more corresponding annulargrooves positioned on the bullet. The forward opening end is crimped sothat a polymeric material flows into an annular groove of a bullet. Inone embodiment the bullet is adhesively fitted to the forward openingend; however, in other embodiment, the bullet is fitted to the forwardopening end by welding or bonding together using solvent, adhesive,spin-welding, vibration-welding, ultrasonic-welding or laser-weldingtechniques.

In one embodiment the substantially cylindrical polymeric bullet-endincludes a cannelure or mechanical interlock for engagement between theforward opening end and a bullet at the shoulder end of the forwardopening end. Although the mechanical interlock is located in the lowerportion of the bullet at the shoulder end it may also be located at anyposition from the entrance or the end of the cylindrical polymericbullet-end. Furthermore, the mechanical interlock/cannelure may include1, 2, 3, 4, 5, or more mechanical interlocks/cannelures. Thesubstantially cylindrical polymeric bullet-end may be connected to thebullet through an adhesive or weld. In addition, a combination ofadhesives or welds, etc and 1, 2, 3, 4, 5, or more mechanicalinterlocks/cannelures may be used.

The substantially cylindrical polymeric bullet-end may include a forwardopening end having a first and a second mechanical interlock forengagement between the forward opening end and a bullet. In oneembodiment the forward opening end includes two or more canneluresformed on an outer circumferential surface of the forward opening end.In one embodiment the forward opening end comprises one, two or moreannular rings that mate with one, two or more corresponding annulargrooves positioned on the bullet. The forward opening end is crimped sothat a polymeric material flows into an annular groove of a bullet. Inone embodiment the bullet is adhesively fitted to the forward openingend; however, in other embodiment, the bullet is fitted to the forwardopening end by welding or bonding together using solvent, adhesive,spin-welding, vibration-welding, ultrasonic-welding or laser-weldingtechniques.

In one embodiment the substantially cylindrical polymeric middle bodyincludes polymers selected from the group consisting of polyurethaneprepolymer, cellulose, fluoro-polymer, ethylene inter-polymer alloyelastomer, ethylene vinyl acetate, nylon, polyether imide, polyesterelastomer, polyester sulfone, polyphenyl amide, polypropylene,polyvinylidene fluoride or thermoset polyurea elastomer, acrylics,homopolymers, acetates, copolymers, acrylonitrile-butadinen-styrene,thermoplastic fluoro polymers, inomers, polyamides, polyamide-imides,polyacrylates, polyatherketones, polyaryl-sulfones, polybenzimidazoles,polycarbonates, polybutylene, terephthalates, polyether imides,polyether sulfones, thermoplastic polyimides, thermoplasticpolyurethanes, polyphenylene sulfides, polyethylene, polypropylene,polysulfones, polyvinylchlorides, styrene acrylonitriles, polystyrenes,polyphenylene, ether blends, styrene maleic anhydrides, polycarbonates,allyls, aminos, cyanates, epoxies, phenolics, unsaturated polyesters,bismaleimides, polyurethanes, silicones, vinylesters, urethane hybrids,polyphenylsulfones, copolymers of polyphenylsulfones withpolyethersulfones or polysulfones, copolymers of poly-phenylsulfoneswith siloxanes, blends of polyphenylsulfones with polysiloxanes,poly(etherimide-siloxane) copolymers, blends of polyetherimides andpolysiloxanes, and blends of polyetherimides andpoly(etherimide-siloxane) copolymers.

The forward opening end comprises a neck with a plurality of internalstructures for supporting a bullet. The substantially cylindricalcoupling element is a male coupling element with a straight skirtinterlock surface that tapers to a smaller diameter at the forwardportion on the skirt tip to mate with a female coupling element of thesubstantially cylindrical polymeric coupling end. In one embodiment thepolymeric ammunition cartridge further includes a diffuser positioned inthe primer recess comprising a diffuser flash hole aligned with theprimer flash hole.

Another embodiment of the polymeric ammunition cartridge having adiffuser of the present invention includes a substantially cylindricalinsert, a diffuser, and a substantially cylindrical polymeric middlebody. The substantially cylindrical insert includes a top surfaceopposite a bottom surface and a substantially cylindrical couplingelement that extends from the bottom surface, a primer recess in the topsurface that extends toward the bottom surface, a primer flash holepositioned in the primer recess to extend through the bottom surface,and a flange that extends circumferentially about an outer edge of thetop surface. The diffuser positioned in the primer recess comprising adiffuser flash hole aligned with the primer flash hole. Thesubstantially cylindrical polymeric middle body includes a substantiallycylindrical polymeric bullet-end and a substantially cylindricalpolymeric coupling end connected by a powder chamber, wherein thesubstantially cylindrical polymeric coupling end extends over thesubstantially cylindrical coupling element and covers a circumferentialsurface of the primer flash hole. The diffuser has a primer flash holewith a flash hole lip extending into a bore of the primer flash hole.

Another embodiment of the polymeric ammunition cartridge of the presentinvention includes a substantially cylindrical insert having a topsurface opposite a bottom surface and a substantially cylindricalcoupling element that extends from the bottom surface, a primer recessin the top surface that extends toward the bottom surface, a primerflash hole positioned in the primer recess to extend through the bottomsurface, and a flange that extends circumferentially about an outer edgeof the top surface; a substantially cylindrical polymeric middle bodycomprising a substantially cylindrical polymeric bullet-end and asubstantially cylindrical polymeric coupling end connected by a powderchamber, wherein the substantially cylindrical polymeric coupling endextends over the substantially cylindrical coupling element and coversan circumferential surface of the primer flash hole; and a substantiallycylindrical polymeric bullet-end upper portion comprising a bullet-endcoupling element connected to the substantially cylindrical polymericbullet-end and a forward opening end to engage a bullet.

Another embodiment of the polymeric ammunition cartridge of the presentinvention includes a metal insert for a polymeric ammunition cartridgehaving a top surface opposite a bottom surface and a substantiallycylindrical coupling element that extends from the bottom surface, aprimer recess in the top surface that extends toward the bottom surface,a primer flash hole positioned in the primer recess to extend throughthe bottom surface, and a flange that extends circumferentially about anouter edge of the top surface. In other embodiments the polymericammunition cartridge, further includes a diffuser positioned in theprimer recess comprising a diffuser flash hole aligned with the primerflash hole.

Another embodiment of the polymeric ammunition cartridge of the presentinvention includes a polymer insert for a polymeric ammunition cartridgehaving a top surface opposite a bottom surface and a substantiallycylindrical coupling element that extends from the bottom surface, aprimer recess in the top surface that extends toward the bottom surface,a primer flash hole positioned in the primer recess to extend throughthe bottom surface, and a flange that extends circumferentially about anouter edge of the top surface. In other embodiments the polymericammunition cartridge, further includes a diffuser positioned in theprimer recess.

Still another embodiment includes a method of forming a polymericammunition cartridge by providing a substantially cylindrical inserthaving a top surface opposite a bottom surface and a substantiallycylindrical coupling element that extends from the bottom surface, aprimer recess in the top surface that extends toward the bottom surface,a primer flash hole positioned in the primer recess to extend throughthe bottom surface, and a flange that extends circumferentially about anouter edge of the top surface, forming a substantially cylindricalpolymeric middle body comprising a substantially cylindrical polymericbullet-end and a substantially cylindrical polymeric coupling endconnected by a powder chamber, connecting the substantially cylindricalpolymeric coupling end to the substantially cylindrical couplingelement; and covering circumferentially an interior surface of theprimer flash hole. The method further includes the step of positioning adiffuser comprising a diffuser flash hole in the primer recess andaligning the diffuser flash hole with the primer flash hole.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

For a more complete understanding of the features and advantages of thepresent invention, reference is now made to the detailed description ofthe invention along with the accompanying figures and in which:

FIG. 1 depicts a side, cross-sectional view of a polymeric cartridgecase according to one embodiment of the present invention;

FIG. 2 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case according to one embodiment of the presentinvention;

FIG. 3 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case lacking the aperture coating;

FIGS. 4a and 4b depict images of a catastrophic failure of the polymericcartridge case of FIG. 3;

FIG. 5 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case displaying ribs according to one embodiment ofthe present invention;

FIG. 6 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case displaying ribs according to one embodiment ofthe present invention;

FIG. 7 depicts a side, cross-sectional view of a polymeric cartridgecase having a diffuser according to one embodiment of the presentinvention;

FIG. 8 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case having a diffuser according to one embodimentof the present invention;

FIGS. 9a-9h depict the diffuser according to a different embodiment ofthe present invention;

FIG. 10 depicts an exploded view of the polymeric cartridge casing;

FIG. 11 depicts a view of the substantially cylindrical open-endedpolymeric bullet-end having a shoulder forming chamber neck and abullet; and

FIG. 12 depicts an elevation view of a bullet-end component of thepolymeric cartridge casing; and

FIG. 13 depicts a side, cross-sectional view of a bullet-end componentof the polymeric cartridge casing.

DETAILED DESCRIPTION OF THE INVENTION

While the making and using of various embodiments of the presentinvention are discussed in detail below, it should be appreciated thatthe present invention provides many applicable inventive concepts thatcan be embodied in a wide variety of specific contexts. The specificembodiments discussed herein are merely illustrative of specific ways tomake and use the invention and do not delimit the scope of theinvention.

To facilitate the understanding of this invention, a number of terms aredefined below. Terms defined herein have meanings as commonly understoodby a person of ordinary skill in the areas relevant to the presentinvention. Terms such as “a”, “an” and “the” are not intended to referto only a singular entity, but include the general class of which aspecific example may be used for illustration. The terminology herein isused to describe specific embodiments of the invention, but their usagedoes not delimit the invention, except as outlined in the claims.

Reliable cartridge manufacture requires uniformity from one cartridge tothe next in order to obtain consistent ballistic performance. Amongother considerations, proper bullet seating and bullet-to-casing fit isrequired. In this manner, a desired pressure develops within the casingduring firing prior to bullet and casing separation. Historically,bullets employ a cannelure, which is a slight annular depression formedin a surface of the bullet at a location determined to be the optimalseating depth for the bullet. In this manner, a visual inspection of acartridge could determine whether or not the bullet is seated at theproper depth. Once the bullet is inserted into the casing to the properdepth, one of two standard procedures is incorporated to lock the bulletin its proper location. One method is the crimping of the entire end ofthe casing into the cannelure. A second method does not crimp the casingend; rather the bullet is pressure fitted into the casing.

The polymeric ammunition cartridges of the present invention are of acaliber typically carried by soldiers in combat for use in their combatweapons. The present invention is not limited to the described caliberand is believed to be applicable to other calibers as well. Thisincludes various small and medium caliber munitions, including 5.56 mm,7.62 mm and .50 caliber ammunition cartridges, as well as medium/smallcaliber ammunition such as 380 caliber, 38 caliber, 9 mm, 10 mm, 20 mm,25 mm, 30 mm, 40 mm, 45 caliber and the like. The cartridges, therefore,are of a caliber between about .05 and about 5 inches. Thus, the presentinvention is also applicable to the sporting goods industry for use byhunters and target shooters.

FIG. 1 depicts a side, cross-sectional view of a polymeric cartridgecase according to one embodiment of the present invention. A cartridge10 suitable for use with high velocity rifles is shown manufactured witha polymer casing 12 showing a powder chamber 14 with projectile (notshown) inserted into the forward end opening 16. Polymer casing 12 has asubstantially cylindrical open-ended polymeric bullet-end 18 extendingfrom forward end opening 16 rearward to opposite end 20. The bullet-endcomponent 18 may be formed with coupling end 22 formed on end 20.Coupling end 22 is shown as a female element, but may also be configuredas a male element in alternate embodiments of the invention. The forwardend of bullet-end component 18 has a shoulder 24 forming chamber neck26. The bullet-end component typically has a wall thickness betweenabout 0.003 and about 0.200 inches and more preferably between about0.005 and more preferably between about 0.150 inches about 0.010 andabout 0.050 inches.

The middle body component 28 is connected to a substantially cylindricalcoupling element 30 of the substantially cylindrical insert 32. Couplingelement 30, as shown may be configured as a male element, however, allcombinations of male and female configurations is acceptable forcoupling elements 30 and coupling end 22 in alternate embodiments of theinvention. Coupling end 22 of bullet-end component 18 fits about andengages coupling element 30 of a substantially cylindrical insert 32.The substantially cylindrical insert 32 includes a substantiallycylindrical coupling element 30 extending from a bottom surface 34 thatis opposite a top surface 36. Located in the top surface 36 is a primerrecess 38 that extends toward the bottom surface 34. A primer flash hole40 extends through the bottom surface 34 into the powder chamber 14. Thecoupling end 22 extends the polymer through the primer flash hole 40 toform an aperture coating 42 while retaining a passage from the topsurface 36 through the bottom surface 34 and into the powder chamber 14to provide support and protection about the primer flash hole 40. Whencontacted the coupling end 22 interlocks with the substantiallycylindrical coupling element 30, through the coupling element 30 thatextends with a taper to a smaller diameter at the tip 44 to form aphysical interlock between substantially cylindrical insert 32 andmiddle body component 28. Polymer casing 12 also has a substantiallycylindrical open-ended middle body component 28. The middle bodycomponent extends from a forward end opening 16 to coupling element 22.The middle body component typically has a wall thickness of betweenabout 0.003 and about 0.200 inches and more preferably between about0.005 and about 0.150 inches; or about 0.010 and about 0.050 inches.

The bullet-end 16, middle body 18 and bottom surface 34 define theinterior of powder chamber 14 in which the powder charge (not shown) iscontained. The interior volume of powder chamber 14 may be varied toprovide the volume necessary for complete filling of the chamber 14 bythe propellant chosen so that a simplified volumetric measure ofpropellant can be utilized when loading the cartridge. Either aparticulate or consolidated propellant can be used.

The substantially cylindrical insert 32 also has a flange 46 cut thereinand a primer recess 38 formed therein for ease of insertion of theprimer (not shown). The primer recess 38 is sized so as to receive theprimer (not shown) in an interference fit during assembly. A primerflash hole 40 communicates through the bottom surface 34 ofsubstantially cylindrical insert 32 into the powder chamber 14 so thatupon detonation of primer (not shown) the powder in powder chamber 14will be ignited.

Projectile (not shown) is held in place within chamber case neck 26 atforward opening 16 by an interference fit. Mechanical crimping of theforward opening 16 can also be applied to increase the bullet pullforce. The bullet (not shown) may be inserted into place following thecompletion of the filling of powder chamber 14. Projectile (not shown)can also be injection molded directly onto the forward opening 16 priorto welding or bonding together using solvent, adhesive, spin-welding,vibration-welding, ultrasonic-welding or laser-welding techniques. Thewelding or bonding increases the joint strength so the casing can beextracted from the hot gun casing after firing at the cook-offtemperature.

The bullet-end and bullet components can then be welded or bondedtogether using solvent, adhesive, spin-welding, vibration-welding,ultrasonic-welding or laser-welding techniques. The welding or bondingincreases the joint strength so the casing can be extracted from the hotgun casing after firing at the cook-off temperature. An optional firstand second annular grooves (cannelures) may be provided in thebullet-end in the interlock surface of the male coupling element toprovide a snap-fit between the two components. The cannelures formed ina surface of the bullet at a location determined to be the optimalseating depth for the bullet. Once the bullet is inserted into thecasing to the proper depth to lock the bullet in its proper location.One method is the crimping of the entire end of the casing into thecannelures.

The bullet-end and middle body components can then be welded or bondedtogether using solvent, adhesive, spin-welding, vibration-welding,ultrasonic-welding or laser-welding techniques. The welding or bondingincreases the joint strength so the casing can be extracted from the hotgun casing after firing at the cook-off temperature.

FIG. 2 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case according to one embodiment of the presentinvention. A portion of a cartridge suitable for use with high velocityrifles is shown manufactured with a polymer casing (not shown) showing apowder chamber 14. Polymer casing (not shown) has a substantiallycylindrical opposite end 20. The bullet-end component (not shown) may beformed with coupling end 22 formed on end 20. Coupling end 22 is shownas a female element, but may also be configured as a male element inalternate embodiments of the invention. The middle body component (notshown) is connected to a substantially cylindrical coupling element 30of the substantially cylindrical insert 32. Coupling element 30, asshown may be configured as a male element, however, all combinations ofmale and female configurations are acceptable for coupling elements 30and coupling end 22 in alternate embodiments of the invention. Couplingend 22 fits about and engages coupling element 30 of a substantiallycylindrical insert 32. The substantially cylindrical insert 32 includesa substantially cylindrical coupling element 30 extending from a bottomsurface 34 that is opposite a top surface 36. Located in the top surface36 is a primer recess 38 that extends toward the bottom surface 34. Aprimer flash hole 40 is located in the primer recess 28 and extendsthrough the bottom surface 34 into the powder chamber 14. The couplingend 22 extends the polymer through the primer flash hole 40 to form anaperture coating 42 while retaining a passage from the top surface 36through the bottom surface 34 and into the powder chamber 14 to providesupport and protection about the primer flash hole 40. When contactedthe coupling end 22 interlocks with the substantially cylindricalcoupling element 30, through the coupling element 30 that extends with ataper to a smaller diameter at the tip 44 to form a physical interlockbetween substantially cylindrical insert 32 also has a flange 46 cuttherein and middle body component 28. Polymer casing 12 also has asubstantially cylindrical open-ended middle body component 28.

FIG. 3 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case lacking the aperture coating (not shown). Aportion of a cartridge suitable for use with high velocity rifles isshown manufactured with a polymer casing (not shown) showing a powderchamber 14. Polymer casing (not shown) has a substantially cylindricalopposite end 20. The bullet-end component (not shown) may be formed withcoupling end 22 formed on end 20. Coupling end 22 is shown as a femaleelement, but may also be configured as a male element in alternateembodiments of the invention. The middle body component (not shown) isconnected to a substantially cylindrical coupling element 30 of thesubstantially cylindrical insert 32. Coupling element 30, as shown maybe configured as a male element, however, all combinations of male andfemale configurations are acceptable for coupling elements 30 andcoupling end 22 in alternate embodiments of the invention. Coupling end22 fits about and engages coupling element 30 of a substantiallycylindrical insert 32. The substantially cylindrical insert 32 includesa substantially cylindrical coupling element 30 extending from a bottomsurface 34 that is opposite a top surface 36. Located in the top surface36 is a primer recess 38 that extends toward the bottom surface 34. Aprimer flash hole (not shown) is located in the primer recess 28 andextends through the bottom surface 34 into the powder chamber 14. Whencontacted the coupling end 22 interlocks with the substantiallycylindrical coupling element 30, through the coupling element 30 thatextends with a taper to a smaller diameter at the tip (not shown) toform a physical interlock between substantially cylindrical insert 32also has a flange 46 cut therein and middle body component (not shown).

FIGS. 4a and 4b depict images of a catastrophic failure of the polymericcartridge case of FIG. 3. Other polymeric cartridge case was tested andresulted in catastrophic failure with the rounds blowing the magazineout of the weapon and fragmenting the metal insert and lodging thepolymer case in the chamber. The examination of the catastrophic failurerevealed the tearing of the polymer at the top of the insert. As aresult, in some embodiments the height of the insert was reduced by0.020″ to reduce the tearing and frequency of catastrophic failures.Further examination, revealed that the polymer at the flash hole of thebase was separating from the insert. One embodiment locks the polymerinto the flash hole by extending the polymer into the flash hole. Inaddition, the raised area was removed, the diameter of the flash holewas opened, and the primer side was counter bored. Other embodiments mayincorporate all, one, or a combination of 2 or more of these elements tostop the gas from separating the polymer from the insert that wascreating combustion between the insert and the polymer.

FIG. 5 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case displaying ribs according to one embodiment ofthe present invention. A portion of a cartridge suitable for use withhigh velocity rifles is shown manufactured with a polymer casing (notshown) showing a powder chamber 14. Polymer casing (not shown) has asubstantially cylindrical opposite end 20. The bullet-end component 18may be formed with coupling end 22 formed on end 20. Coupling end 22 isshown as a female element, but may also be configured as a male elementin alternate embodiments of the invention. The middle body component(not shown) is connected to a substantially cylindrical coupling element30 of the substantially cylindrical insert 32. Coupling element 30, asshown may be configured as a male element, however, all combinations ofmale and female configurations is acceptable for coupling elements 30and coupling end 22 in alternate embodiments of the invention. Couplingend 22 fits about and engages coupling element 30 of a substantiallycylindrical insert 32. The substantially cylindrical insert 32 includesa substantially cylindrical coupling element 30, extending from a bottomsurface 34 that is opposite a top surface 36. Located in the top surface36 is a primer recess 38 that extends toward the bottom surface 34. Aprimer flash hole 40 is located in the primer recess 28 and extendsthrough the bottom surface 34 into the powder chamber 14. The couplingend 22 extends the polymer through the primer flash hole 40 to form anaperture coating 42 while retaining a passage from the top surface 36through the bottom surface 34 and into the powder chamber 14 to providesupport and protection about the primer flash hole 40. When contactedthe coupling end 22 interlocks with the substantially cylindricalcoupling element 30, through the coupling element 30 that extends with ataper to a smaller diameter at the tip 44 to form a physical interlockbetween substantially cylindrical insert 32 also has a flange 46 cuttherein and middle body component 28. Polymer casing (not shown) alsohas a substantially cylindrical open-ended middle body component 28. Thesubstantially cylindrical opposite end 20 or anywhere within the powderchamber 14 may include one or more ribs 48 on the surface. The number ofribs 48 will depend on the specific application and desire of themanufacture but may include 1, 2, 3, 4, 5 6, 7, 8, 9, 10, or more ribs.In the counter bore, the polymer was having difficulty filling this areadue to the fact that the polymer used has fillers in it, and needed tobe reblended during molding. One embodiment includes six ribs 48 tocreate turbulence in the flow of the polymer, thus allowing the materialto fill the counter bore.

FIG. 6 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case displaying ribs according to one embodiment ofthe present invention. One embodiment that reduces bellowing of theinsert includes a shortened insert and angled coupling element 30 insideof the insert. In addition, the raised portion of the polymer at theflash hole was removed, the internal polymer wall was lowered and angledto match the insert and the internal ribs were lengthened.

A portion of a cartridge suitable for use with high velocity rifles isshown manufactured with a polymer casing (not shown) showing a powderchamber 14. Polymer casing (not shown) has a substantially cylindricalopposite end 20. The bullet-end component (not shown) may be formed withcoupling end 22 formed on end 20. Coupling end 22 is shown as a femaleelement, but may also be configured as a male element in alternateembodiments of the invention. The middle body component (not shown) isconnected to a substantially cylindrical coupling element 30 of thesubstantially cylindrical insert 32. Coupling element 30, as shown maybe configured as a male element, however, all combinations of male andfemale configurations are acceptable for coupling elements 30 andcoupling end 22 in alternate embodiments of the invention. Coupling end22 fits about and engages coupling element 30 of a substantiallycylindrical insert 32. The substantially cylindrical insert 32 includesa substantially cylindrical coupling element 30 extending from a bottomsurface 34 that is opposite a top surface 36. Located in the top surface36 is a primer recess 38 that extends toward the bottom surface 34. Aprimer flash hole 40 is located in the primer recess 28 and extendsthrough the bottom surface 34 into the powder chamber 14. The couplingend 22 extends the polymer through the primer flash hole 40 to form anaperture coating 42 while retaining a passage from the top surface 36through the bottom surface 34 and into the powder chamber 14 to providesupport and protection about the primer flash hole 40. When contactedthe coupling end 22 interlocks with the substantially cylindricalcoupling element 30, through the coupling element 30 that extends with ataper to a smaller diameter at the tip 44 to form a physical interlockbetween substantially cylindrical insert 32 and middle body component28. Polymer casing (not shown) also has a substantially cylindricalopen-ended middle body component 28. The substantially cylindricalopposite end 20 or anywhere within the powder chamber 14 may include oneor more ribs 48 on the surface. The number of ribs 48 will depend on thespecific application and desire of the manufacture but may include 1, 2,3, 4, 5 6, 7, 8, 9, 10, or more ribs. In the counter bore, the polymerwas having difficulty filling this area due to the fact that the polymerused has fillers in it, and needed to be reblended during molding. Oneembodiment includes six ribs 48 to create turbulence in the flow of thepolymer, thus allowing the material to fill the counter bore. Anotherembodiment of the present invention is a shortened insert and angledcoupling element 30 inside of the insert. In addition, raised portionsof the polymer at the flash hole, lowered and angled the internalpolymer wall to match the insert and lengthened the internal ribs.

FIG. 7 depicts a side, cross-sectional view of a polymeric cartridgecase having a diffuser according to one embodiment of the presentinvention. The diffuser (not shown) is a device that is used to divertthe affects of the primer off of the polymer and directing it to theflash hole. The affects being the impact from igniting the primer as faras pressure and heat. A cartridge 10 suitable for use with high velocityrifles is shown manufactured with a polymer casing (not shown) showing apowder chamber 14 with projectile (not shown) inserted into the forwardend opening 16. Polymer casing (not shown) has a substantiallycylindrical open-ended polymeric bullet-end 18 extending from forwardend opening 16 rearward to the opposite end 20. The bullet-end component(not shown) may be formed with coupling end 22 formed on end 20.Coupling end 22 is shown as a female element, but may also be configuredas a male element in alternate embodiments of the invention. The forwardend of bullet-end component 18 has a shoulder 24 forming chamber neck26.

The middle body component 28 is connected to a substantially cylindricalcoupling element 30 of the substantially cylindrical insert 32. Couplingelement 30, as shown may be configured as a male element, however, allcombinations of male and female configurations is acceptable forcoupling elements 30 and coupling end 22 in alternate embodiments of theinvention. Coupling end 22 of bullet-end component 18 fits about andengages coupling element 30 of a substantially cylindrical insert 32.The substantially cylindrical insert 32 includes a substantiallycylindrical coupling element 30 extending from a bottom surface 34 thatis opposite a top surface 36. Located in the top surface 36 is a primerrecess 38 that extends toward the bottom surface 34. A primer flash hole40 is located in the primer recess 28 and extends through the bottomsurface 34 into the powder chamber 14. The coupling end 22 extends thepolymer through the primer flash hole 40 to form an aperture coating 42while retaining a passage from the top surface 36 through the bottomsurface 34 and into the powder chamber 14 to provides support andprotection about the primer flash hole 40. When contacted the couplingend 22 interlocks with the substantially cylindrical coupling element30, through the coupling element 30 that extends with a taper to asmaller diameter at the tip 44 to form a physical interlock betweensubstantially cylindrical insert 32 also has a flange 46 cut therein andmiddle body component 28. Polymer casing 12 also has a substantiallycylindrical open-ended middle body component 28. The middle bodycomponent extends from a forward end opening 16 to coupling element 22.Located in the top surface 36 is a primer recess 38 that extends towardthe bottom surface 34 with a diffuser (not shown) positioned in theprimer recess 38. The diffuser (not shown) includes a diffuser aperture(not shown) that aligns with the primer flash hole 40. The diffuser (notshown) is a device that is used to divert the affects of the primer (notshown) off of the polymer. The affects being the impact from ignitingthe primer as far as pressure and heat to divert the energy of theprimer off of the polymer and directing it to the flash hole.

FIG. 8 depicts a side, cross-sectional view of a portion of thepolymeric cartridge case having a diffuser according to one embodimentof the present invention. A portion of a cartridge suitable for use withhigh velocity rifles is shown manufactured with a polymer casing (notshown) showing a powder chamber 14. Polymer casing (not shown) has asubstantially cylindrical opposite end 20. The bullet-end component (notshown) may be formed with coupling end 22 formed on end 20. Coupling end(not shown) is shown as a female element, but may also be configured asa male element in alternate embodiments of the invention. The middlebody component (not shown) is connected to a substantially cylindricalcoupling element 30 of the substantially cylindrical insert 32. Couplingelement 30, as shown may be configured as a male element, however, allcombinations of male and female configurations are acceptable forcoupling elements 30 and coupling end (not shown) in alternateembodiments of the invention. Coupling end (not shown) fits about andengages coupling element 30 of a substantially cylindrical insert 32.The substantially cylindrical insert 32 includes a substantiallycylindrical coupling element 30 extending from a bottom surface (notshown) that is opposite a top surface 36. Located in the top surface 36is a primer recess 38 that extends toward the bottom surface (notshown). A primer flash hole 40 extends through the bottom surface (notshown) into the powder chamber 14. The coupling end (not shown) extendsthe polymer through the primer flash hole 40 to form an aperture coating42 while retaining a passage from the top surface 36 through the bottomsurface (not shown) and into the powder chamber 14 to provides supportand protection about the primer flash hole 40. When contacted thecoupling end (not shown) interlocks with the substantially cylindricalcoupling element 30, through the coupling element 30 that extends with ataper to a smaller diameter at the tip 44 to form a physical interlockbetween substantially cylindrical insert 32 also has a flange 46 cuttherein and middle body component 28. Polymer casing (not shown) alsohas a substantially cylindrical open-ended middle body component 28.Located in the top surface 36 is a primer recess 38 that extends towardthe bottom surface (not shown) with a diffuser 50 positioned in theprimer recess 38. The diffuser (not shown) includes a diffuser aperture52 and a diffuser aperture extension 54 that aligns with the primerflash hole 40. The diffuser 50 is a device that is used to divert theaffects of the primer (not shown) off of the polymer. The affects beingthe impact from igniting the primer as far as pressure and heat todivert the energy of the primer off of the polymer and directing it tothe flash hole. The diffuser 50 can be between 0.004 to 0.010 inches inthickness and made from half hard brass. For example, the diffuser 50can be between 0.005 inches thick for a 5.56 diffuser 50. The OD of thediffuser for a 5.56 or 223 case is 0.173 and the ID is 0.080. TheDiffuser could be made of any material that can withstand the energyfrom the ignition of the primer. This would include steel, stainless,cooper, aluminum or even an engineered resin that was injection moldedor stamped. The Diffuser can be produce in T shape by drawing thematerial with a stamping and draw die. In the T Diffuser the center ringcan be 0.005 to 0.010 tall and the OD is 0.090 and the ID 0.080.

FIGS. 9a-9h depict different embodiment of the diffuser of the presentinvention.

FIG. 10 depicts an exploded view of the polymeric cartridge casing. Acartridge 10 suitable for use with high velocity rifles is shownmanufactured with a middle body component 28 having a substantiallycylindrical open-ended polymeric bullet-end 18 extending from forwardend opening 16 rearward to opposite end 20. A portion of a cartridgesuitable for use with high velocity rifles is shown manufactured with apolymer casing 12 showing a powder chamber 14. Polymer casing 12 has asubstantially cylindrical opposite end 20. The bullet-end component 18may be formed with coupling end 22 formed on end 20. Coupling end 22 isshown as a female element, but may also be configured as a male elementin alternate embodiments of the invention. The middle body component(not shown) is connected to a substantially cylindrical coupling element30 of the substantially cylindrical insert 32. The substantiallycylindrical open-ended polymeric bullet-end 18 has a shoulder 24 formingchamber neck 26 and a bullet 56 inserted therein. The substantiallycylindrical insert 32 also has a flange 46 cut therein and a primerrecess (not shown) formed therein for ease of insertion of the primer(not shown). When contacted the coupling end 22 interlocks with thesubstantially cylindrical coupling element 30, through the couplingelement 30 that extends with a taper to a smaller diameter at the tip 44to form a physical interlock between substantially cylindrical insert 32and middle body component 28. In one embodiment of the presentinvention, the substantially cylindrical insert 32 may be made of ametal that is formed by a metal injection molding process. The modeldesign may be seen in FIGS. 2, 8, 9 and 10.

The molded substantially cylindrical insert 32 is then bound to themiddle body component 28. In the metal injection molding process ofmaking the substantially cylindrical insert 32 a mold is made in theshape of the substantially cylindrical insert 32 including the desiredprofile of the primer recess (not shown). The substantially cylindricalinsert 32 includes a substantially cylindrical coupling element 30extending from a bottom surface 34 that is opposite a top surface (notshown). Located in the top surface (not shown) is a primer recess (notshown) that extends toward the bottom surface 34. A primer flash hole(not shown) is located in the substantially cylindrical insert 32 andextends through the bottom surface 34 into the powder chamber 14. Thecoupling end (not shown) extends through the primer flash hole (notshown) to form an aperture coating (not shown) while retaining a passagefrom the top surface (not shown) through the bottom surface (not shown)and into the powder chamber 14 to provides support and protection aboutthe primer flash hole (not shown). When contacted the coupling end (notshown) interlocks with the substantially cylindrical coupling element30, through the coupling element 30 that extends with a taper to asmaller diameter at the tip (not shown) to form a physical interlockbetween substantially cylindrical insert 32 and middle body component28.

For example, the metal injection molding process, which generallyinvolves mixing fine metal powders with binders to form a feedstock thatis injection molded into a closed mold, may be used to form asubstantially cylindrical insert. After ejection from the mold, thebinders are chemically or thermally removed from the substantiallycylindrical insert so that the part can be sintered to high density.During the sintering process, the individual metal particlesmetallurgically bond together as material diffusion occurs to removemost of the porosity left by the removal of the binder.

The raw materials for metal injection molding are metal powders and athermoplastic binder. There are at least two Binders included in theblend, a primary binder and a secondary binder. This blended powder mixis worked into the plasticized binder at elevated temperature in akneader or shear roll extruder. The intermediate product is theso-called feedstock. It is usually granulated with granule sizes ofseveral millimeters. In metal injection molding, only the binders areheated up, and that is how the metal is carried into the mold cavitywhereas,

In preparing a Feedstock, it is important first to measure the actualdensity of each lot of both the metal powders and binders. This isextremely important especially for the metal powders in that each lotwill be different based on the actual chemistry of that grade of powder.For example, 316L is comprised of several elements, such as Fe, Cr, Ni,Cu, Mo, P, Si, S and C. In order to be rightfully called a 316L, each ofthese elements must meet a minimum and maximum percentage weightrequirement as called out in the relevant specification. Hence thevariation in the chemistry within the specification results in asignificant density variation within the acceptable composition range.Depending on the lot received from the powder producer, the density willvary depending on the actual chemistry received.

Molding Many MIM companies will mold a part until they feel that thecavity has been filled. Both mold design factors such as runner and gatesize, gate placement, venting and molding parameters set on the moldingmachine affect the molded part. A helium Pycnometer can determine ifthere are voids trapped inside the parts. During molding, you have atool that can be used to measure the percent of theoretical densityachieved on the “Green” or molded part. By crushing the measured “green”molded part back to powder, you can now confirm the percent of air (orvoids) trapped in the molded part. To measure this, the density of themolded part should be measured in the helium Pycnometer and compared tothe theoretical density of the feedstock. Then, take the same moldedpart that was used in the density test and crush it back to powder. Ifthis granulate shows a density of more than 100% of that of thefeedstock, then some of the primary binders have been lost during themolding process. The molding process needs to be corrected because usingthis process with a degraded feedstock will result in a larger shrinkageand result in a part smaller than that desired. It is vital to be surethat your molded parts are completely filled before continuing themanufacturing process for debinding and sintering. The helium Pycnometerprovides this assurance. Primary debinding properly debound parts areextremely important to establish the correct sintering profile. Theprimary binder must be completely removed before attempting to start toremove the secondary binder as the secondary binder will travel throughthe pores created by the extraction of the primary binder. Primarydebinding techniques depend on the feedstock type used to make theparts. However the feedstock supplier knows the amount of primarybinders that have been added and should be removed before proceeding tothe next process step. The feedstock supplier provides a minimum “browndensity” that must be achieved before the parts can be moved into afurnace for final debinding and sintering. This minimum brown densitywill take into account that a small amount of the primary binder remnantmay be present and could be removed by a suitable hold during secondarydebinding and sintering. The sintering profile should be adjusted toremove the remaining small percent of primary binder before the removalof the secondary binder. Most external feedstock manufacturers provideonly a weight loss percent that should be obtained to define suitabledebinding. Solvent debound parts must be thoroughly dried, before thehelium Pycnometer is used to determine the “brown” density so that theremnant solvent in the part does not affect the measured density value.When the feedstock manufacturer gives you the theoretical density of the“brown” or debound part, can validate the percent of debinding that hasbeen achieved. Most MIM operations today perform the secondary debindingand sintering in the same operation. Every MIM molder has gates andrunners left over from molding their parts. So, you will be able to nowre-use your gates and runners with confidence that they will shrinkcorrectly after sintering. If the feedstock producers have given you theactual and theoretical densities of their feedstock, you can easilymeasure the densities of the gates and runners and compare the resultsto the values supplied. Once the regrind densities are higher than thatrequired to maintain the part dimensions, the regrinds are no longerreusable.

Feedstock in accordance with the present invention may be prepared byblending the powdered metal with the binder and heating the blend toform a slurry. Uniform dispersion of the powdered metal in the slurrymay be achieved by employing high shear mixing. The slurry may then becooled to ambient temperature and then granulated to provide thefeedstock for the metal injection molding.

The amount of powdered metal and binder in the feedstock may be selectedto optimize moldability while insuring acceptable green densities. Inone embodiment, the feedstock used for the metal injection moldingportion of the invention may include at least about 40 percent by weightpowdered metal, in another about 50 percent by weight powdered metal ormore. In one embodiment, the feedstock includes at least about 60percent by weight powdered metal, preferably about 65 percent by weightor more powdered metal. In yet another embodiment, the feedstockincludes at least about 75 percent by weight powdered metal. In yetanother embodiment, the feedstock includes at least about 80 percent byweight powdered metal. In yet another embodiment, the feedstock includesat least about 85 percent by weight powdered metal. In yet anotherembodiment, the feedstock includes at least about 90 percent by weightpowdered metal.

The binding agent may be any suitable binding agent that does notdestroy or interfere with the powdered metals. The binder may be presentin an amount of about 50 percent or less by weight of the feedstock. Inone embodiment, the binder is present in an amount ranging from 10percent to about 50 percent by weight. In another embodiment, the binderis present in an amount of about 25 percent to about 50 percent byweight of the feedstock. In another embodiment, the binder is present inan amount of about 30 percent to about 40 percent by weight of thefeedstock. In one embodiment, the binder is an aqueous binder. Inanother embodiment, the binder is an organic-based binder. Examples ofbinders include, but are not limited to, thermoplastic resins, waxes,and combinations thereof. Non-limiting examples of thermoplastic resinsinclude polyolefins such as acrylic polyethylene, polypropylene,polystyrene, polyvinyl chloride, polyethylene carbonate, polyethyleneglycol, and mixtures thereof. Suitable waxes include, but are notlimited to, microcrystalline wax, bee wax, synthetic wax, andcombinations thereof.

Examples of suitable powdered metals for use in the feedstock include,but are not limited to: stainless steel including martensitic andaustenitic stainless steel, steel alloys, tungsten alloys, soft magneticalloys such as iron, iron-silicon, electrical steel, iron-nickel(50Ni-50F3), low thermal expansion alloys, or combinations thereof. Inone embodiment, the powdered metal is a mixture of stainless steel,brass and tungsten alloy. The stainless steel used in the presentinvention may be any 1 series carbon steels, 2 series nickel steels, 3series nickel-chromium steels, 4 series molybdenum steels, serieschromium steels, 6 series chromium-vanadium steels, 7 series tungstensteels, 8 series nickel-chromium-molybdenum steels, or 9 seriessilicon-manganese steels, e.g., 102, 174, 201, 202, 300, 302, 303, 304,308, 309, 316, 316L, 316Ti, 321, 405, 408, 409, 410, 416, 420, 430, 439,440, 446 or 601-665 grade stainless steel.

As known to those of ordinary skill in the art, stainless steel is analloy of iron and at least one other component that imparts corrosionresistance. As such, in one embodiment, the stainless steel is an alloyof iron and at least one of chromium, nickel, silicon, molybdenum, ormixtures thereof. Examples of such alloys include, but are not limitedto, an alloy containing about 1.5 to about 2.5 percent nickel, no morethan about 0.5 percent molybdenum, no more than about 0.15 percentcarbon, and the balance iron with a density ranging from about 7 g/cm³to about 8 g/cm³; an alloy containing about 6 to about 8 percent nickel,no more than about 0.5 percent molybdenum, no more than about 0.15percent carbon, and the balance iron with a density ranging from about 7g/cm³ to about 8 g/cm³; an alloy containing about 0.5 to about 1 percentchromium, about 0.5 percent to about 1 percent nickel, no more thanabout 0.5 percent molybdenum, no more than about 0.2 percent carbon, andthe balance iron with a density ranging from about 7 g/cm³ to about 8g/cm³; an alloy containing about 2 to about 3 percent nickel, no morethan about 0.5 percent molybdenum, about 0.3 to about 0.6 percentcarbon, and the balance iron with a density ranging from about 7 g/cm³to about 8 g/cm³; an alloy containing about 6 to about 8 percent nickel,no more than about 0.5 percent molybdenum, about 0.2 to about 0.5percent carbon, and the balance iron with a density ranging from about 7g/cm³ to about 8 g/cm³; an alloy containing about 1 to about 1.6 percentchromium, about 0.5 percent or less nickel, no more than about 0.5percent molybdenum, about 0.9 to about 1.2 percent carbon, and thebalance iron with a density ranging from about 7 g/cm³ to about 8 g/cm³;and combinations thereof.

Suitable tungsten alloys include an alloy containing about 2.5 to about3.5 percent nickel, about 0.5 percent to about 2.5 percent copper oriron, and the balance tungsten with a density ranging from about 17.5g/cm³ to about 18.5 g/cm³; about 3 to about 4 percent nickel, about 94percent tungsten, and the balance copper or iron with a density rangingfrom about 17.5 g/cm³ to about 18.5 g/cm³; and mixtures thereof.

In addition, the binders may contain additives such as antioxidants,coupling agents, surfactants, elasticizing agents, dispersants, andlubricants as disclosed in U.S. Pat. No. 5,950,063, which is herebyincorporated by reference in its entirety. Suitable examples ofantioxidants include, but are not limited to thermal stabilizers, metaldeactivators, or combinations thereof. In one embodiment, the binderincludes about 0.1 to about 2.5 percent by weight of the binder of anantioxidant. Coupling agents may include but are not limited totitanate, aluminate, silane, or combinations thereof. Typical levelsrange between 0.5 and 15% by weight of the binder.

FIG. 11 depicts a view of the substantially cylindrical open-endedpolymeric bullet-end 18 has a shoulder 24 forming chamber neck 26 and abullet (not shown). One embodiment includes modifications to strengthenthe neck of the mouth 60 and to the internal base area 62 to reduce nosetearing and lodging in the chamber. The substantially cylindricalopen-ended polymeric bullet-end 18 illustrates a lock 58 (e.g.,0.030×0.003) and added a step to allow for the lock 58 to flex outduring firing. Polymer was added to the external area to strengthen theneck of the mouth 60 and to the internal base area 62. The interferenceof the bullet to the neck was increased by adding polymer to the insideof the neck 64 and the exit lock modified by adding an angle to the rim66.

The polymeric and composite casing components may be injection molded.Polymeric materials for the bullet-end and middle body components musthave propellant compatibility and resistance to gun cleaning solventsand grease, as well as resistance to chemical, biological andradiological agents. The polymeric materials must have a temperatureresistance higher than the cook-off temperature of the propellant,typically about 320° F. The polymeric materials must haveelongation-to-break values that to resist deformation under interiorballistic pressure as high as 60,000 psi in all environments(temperatures from about −65 to about 320° F. and humidity from 0 to100% RH). According to one embodiment, the middle body component iseither molded onto or snap-fit to the casing head-end component afterwhich the bullet-end component is snap-fit or interference fit to themiddle body component. The components may be formed from high-strengthpolymer, composite or ceramic.

Examples of suitable high strength polymers include composite polymermaterial including a tungsten metal powder, nylon 6/6, nylon 6, andglass fibers; and a specific gravity in a range of 3-10. The tungstenmetal powder may be 50%-96% of a weight of the bullet body. The polymermaterial also includes about 0.5-15%, preferably about 1-12%, and mostpreferably about 2-9% by weight, of nylon 6/6, about 0.5-15%, preferablyabout 1-12%, and most preferably about 2-9% by weight, of nylon 6, andabout 0.5-15%, preferably about 1-12%, and most preferably about 2-9% byweight, of glass fibers. It is most suitable that each of theseingredients be included in amounts less than 10% by weight. Thecartridge casing body may be made of a modified ZYTEL resin, availablefrom E.I. DuPont De Nemours Co., a modified 612 nylon resin, modified toincrease elastic response.

Examples of suitable polymers include polyurethane prepolymer,cellulose, fluoro-polymer, ethylene inter-polymer alloy elastomer,ethylene vinyl acetate, nylon, polyether imide, polyester elastomer,polyester sulfone, polyphenyl amide, polypropylene, polyvinylidenefluoride or thermoset polyurea elastomer, acrylics, homopolymers,acetates, copolymers, acrylonitrile-butadinen-styrene, thermoplasticfluoro polymers, inomers, polyamides, polyamide-imides, polyacrylates,polyatherketones, polyaryl-sulfones, polybenzimidazoles, polycarbonates,polybutylene, terephthalates, polyether imides, polyether sulfones,thermoplastic polyimides, thermoplastic polyurethanes, polyphenylenesulfides, polyethylene, polypropylene, polysulfones, polyvinylchlorides,styrene acrylonitriles, polystyrenes, polyphenylene, ether blends,styrene maleic anhydrides, polycarbonates, allyls, aminos, cyanates,epoxies, phenolics, unsaturated polyesters, bismaleimides,polyurethanes, silicones, vinylesters, or urethane hybrids. Examples ofsuitable polymers also include aliphatic or aromatic polyamide,polyeitherimide, polysulfone, polyphenylsulfone, poly-phenylene oxide,liquid crystalline polymer and polyketone. Examples of suitablecomposites include polymers such as polyphenylsulfone reinforced withbetween about 30 and about 70 weight percent, and preferably up to about65 weight percent of one or more reinforcing materials selected fromglass fiber, ceramic fiber, carbon fiber, mineral fillers, organonanoclay, or carbon nanotube. Preferred reinforcing materials, such aschopped surface-treated E-glass fibers provide flow characteristics atthe above-described loadings comparable to unfilled polymers to providea desirable combination of strength and flow characteristics that permitthe molding of head-end components. Composite components can be formedby machining or injection molding. Finally, the cartridge case mustretain sufficient joint strength at cook-off temperatures. Morespecifically, polymers suitable for molding of the projectile-endcomponent have one or more of the following properties: Yield or tensilestrength at −65° F.>10,000 psi Elongation-to-break at −65° F.>15% Yieldor tensile strength at 73° F.>8,000 psi Elongation-to-break at 73°F.>50% Yield or tensile strength at 320° F.>4,000 psiElongation-to-break at 320° F.>80%. Polymers suitable for molding of themiddle-body component have one or more of the following properties:Yield or tensile strength at −65° F.>10,000 psi Yield or tensilestrength at 73° F.>8,000 psi Yield or tensile strength at 320° F.>4,000psi.

Commercially available polymers suitable for use in the presentinvention thus include polyphenylsulfones; copolymers ofpolyphenylsulfones with polyether-sulfones or polysulfones; copolymersand blends of polyphenylsulfones with polysiloxanes;poly(etherimide-siloxane); copolymers and blends of polyetherimides andpolysiloxanes, and blends of polyetherimides andpoly(etherimide-siloxane) copolymers; and the like. Particularlypreferred are polyphenylsulfones and their copolymers with poly-sulfonesor polysiloxane that have high tensile strength and elongation-to-breakto sustain the deformation under high interior ballistic pressure. Suchpolymers are commercially available, for example, RADEL R5800polyphenylesulfone from Solvay Advanced Polymers. The polymer can beformulated with up to about 10 wt % of one or more additives selectedfrom internal mold release agents, heat stabilizers, anti-static agents,colorants, impact modifiers and UV stabilizers.

The polymers of the present invention can also be used for conventionaltwo-piece metal-plastic hybrid cartridge case designs and conventionalshotgun shell designs. One example of such a design is an ammunitioncartridge with a one-piece substantially cylindrical polymeric cartridgecasing body with an open projectile-end and an end opposing theprojectile-end with a male or female coupling element; and a cylindricalmetal cartridge casing head-end component with an essentially closedbase end with a primer hole opposite an open end having a couplingelement that is a mate for the coupling element on the opposing end ofthe polymeric cartridge casing body joining the open end of the head-endcomponent to the opposing end of the polymeric cartridge casing body.The high polymer ductility permits the casing to resist breakage.

One embodiment includes a 2 cavity prototype mold having an upperportion and a base portion for a 5.56 case having a metal insertover-molded with a Nylon 6 (polymer) based material. In this embodimentthe polymer in the base includes a lip or flange to extract the casefrom the weapon. One 2-cavity prototype mold to produce the upperportion of the 5.56 case can be made using a stripper plate tool usingan Osco hot spur and two subgates per cavity. Another embodimentincludes a subsonic version, the difference from the standard and thesubsonic version is the walls are thicker thus requiring less powder.This will decrease the velocity of the bullet thus creating a subsonicround.

The extracting inserts is used to give the polymer case a tough enoughridge and groove for the weapons extractor to grab and pull the case outthe chamber of the gun. The extracting insert is made of 17-4 ss that ishardened to 42-45rc. The insert may be made of aluminum, brass, cooper,steel or even an engineered resin with enough tensile strength.

The insert is over molded in an injection molded process using a nanoclay particle filled Nylon material. The inserts can be machined orstamped. In addition, an engineered resin able to withstand the demandon the insert allows injection molded and/or even transfer molded.

One of ordinary skill in the art will know that many propellant typesand weights can be used to prepare workable ammunition and that suchloads may be determined by a careful trial including initial lowquantity loading of a given propellant and the well known stepwiseincreasing of a given propellant loading until a maximum acceptable loadis achieved. Extreme care and caution is advised in evaluating newloads. The propellants available have various burn rates and must becarefully chosen so that a safe load is devised.

FIG. 12 depicts an elevation view of a bullet-end component of thepolymeric cartridge casing. A cartridge (not shown) suitable for usewith high velocity rifles may be manufactured as a modular componentsystem with a middle body component (not shown) with one end beingconnected to a bullet-end component 18 that is connected to a bullet(not shown) inserted therein and the other end being connected to asubstantially cylindrical insert (not shown). As the cartridge (notshown) is made as a modular component system it must be assembled andfused together, e.g., the substantially cylindrical insert (not shown)must be attached to the middle body component (not shown) and thebullet-end component 18 must also be attached to the middle bodycomponent (not shown). In addition, the bullet (not shown) must beattached to the bullet-end component 18 at the forward end opening 16.The bullet-end component 18 has a shoulder 24 forming chamber neck 26and a forward end opening 16 at one end to receive a bullet (not shown)and a powder chamber coupling 68 at the other that mates to the powderchamber (not shown). The forward end opening 16 may include a texturedsurface 70 that extends into the inner neck 64 to enhance the sealing ofthe bullet (not shown) and the bullet-end component 18. The texturedsurface 70 may be in the form of groves, slots, channels, scratches orany other texture to increase the surface area to enhance bonding of thebullet (not shown) and the bullet-end component 18. For example, theforward end opening 16 may include a textured surface 70 of channelsthat extend into the inner neck 64 to enhance the sealing of the bullet(not shown) and the bullet-end component 18. During assembly thetextured surface 70 provides additional surface area for the adhesive tointeract with and thus secure the seal between the bullet (not shown)and the forward end opening 16.

FIG. 13 depicts a side, cross-sectional view of a bullet-end componentof the polymeric cartridge casing. A cartridge (not shown) suitable foruse with high velocity rifles may be manufactured as a modular componentsystem with a middle body component (not shown) with one end beingconnected to a bullet-end component 18 that is connected to a bullet(not shown) inserted therein and the other end being connected to asubstantially cylindrical insert (not shown). The cartridge (not shown)is made as a modular component system it must be assembled and fusedtogether, e.g., the substantially cylindrical insert (not shown) must beattached to the middle body component (not shown) and the bullet-endcomponent 18 must also be attached to the middle body component (notshown). In addition, the bullet (not shown) must be attached to thebullet-end component 18 at the forward end opening 16. The bullet-endcomponent 18 has a shoulder 24 forming chamber neck 26 and a forward endopening 16 at one end to receive a bullet (not shown) and a powderchamber coupling 68 at the other that mates to the powder chamber (notshown). The forward end opening 16 may include a textured surface 70that extends into the inner neck 64 to enhance the sealing of the bullet(not shown) and the bullet-end component 18. The textured surface 70 maybe in the form of groves, slots, channels, scratches or any othertexture to increase the surface area to enhance bonding of the bullet(not shown) and the bullet-end component 18. For example, the forwardend opening 16 may include a textured surface 70 of channels or groovesthat extend into the inner neck 64 to enhance the sealing of the bullet(not shown) and the bullet-end component 18. During assembly thetextured surface 70 provides additional surface area for the adhesive tointeract with and thus secure the seal between the bullet (not shown)and the forward end opening 16. For example the textured surface 70 maybe grooves that extend into the inner neck 64 so that an adhesive whenapplied to the bullet can wick into the grooves and into the inner neck64 to provide a contact area on the bullet and the inner neck 64 for theadhesive. The adhesive can then be cured (e.g., UV light) and sealed.The textured surface 70 may be in any form that allows wicking and/orthe increasing of the surface area, e.g., hatching, grooves, scratches,roughness, etc.

The components may be made of polymeric compositions, metals, ceramics,alloys, or combinations and mixtures thereof. In addition, thecomponents may be mixed and matched with one or more components beingmade of different materials. For example, the middle body component (notshown) may be polymeric; the bullet-end component 18 may be polymeric;and a substantially cylindrical insert (not shown) may be metal.Similarly, the middle body component (not shown) may be polymeric; thebullet-end component 18 may be metal; and a substantially cylindricalinsert (not shown) may be an alloy. The middle body component (notshown) may be polymeric; the bullet-end component 18 may be an alloy;and a substantially cylindrical insert (not shown) may be an alloy. Themiddle body component (not shown); the bullet-end component 18; and/orthe substantially cylindrical insert may be made of a metal that isformed by a metal injection molding process.

The description of the preferred embodiments should be taken asillustrating, rather than as limiting, the present invention as definedby the claims. As will be readily appreciated, numerous combinations ofthe features set forth above can be utilized without departing from thepresent invention as set forth in the claims. Such variations are notregarded as a departure from the spirit and scope of the invention, andall such modifications are intended to be included within the scope ofthe following claims.

It is contemplated that any embodiment discussed in this specificationcan be implemented with respect to any method, kit, reagent, orcomposition of the invention, and vice versa. Furthermore, compositionsof the invention can be used to achieve methods of the invention.

It will be understood that particular embodiments described herein areshown by way of illustration and not as limitations of the invention.The principal features of this invention can be employed in variousembodiments without departing from the scope of the invention. Thoseskilled in the art will recognize, or be able to ascertain using no morethan routine experimentation, numerous equivalents to the specificprocedures described herein. Such equivalents are considered to bewithin the scope of this invention and are covered by the claims.

All publications and patent applications mentioned in the specificationare indicative of the level of skill of those skilled in the art towhich this invention pertains. All publications and patent applicationsare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

The use of the word “a” or “an” when used in conjunction with the term“comprising” in the claims and/or the specification may mean “one,” butit is also consistent with the meaning of “one or more,” “at least one,”and “one or more than one.” The use of the term “or” in the claims isused to mean “and/or” unless explicitly indicated to refer toalternatives only or the alternatives are mutually exclusive, althoughthe disclosure supports a definition that refers to only alternativesand “and/or.” Throughout this application, the term “about” is used toindicate that a value includes the inherent variation of error for thedevice, the method being employed to determine the value, or thevariation that exists among the study subjects.

As used in this specification and claim(s), the words “comprising” (andany form of comprising, such as “comprise” and “comprises”), “having”(and any form of having, such as “have” and “has”), “including” (and anyform of including, such as “includes” and “include”) or “containing”(and any form of containing, such as “contains” and “contain”) areinclusive or open-ended and do not exclude additional, unrecitedelements or method steps.

The term “or combinations thereof” as used herein refers to allpermutations and combinations of the listed items preceding the term.For example, “A, B, C, or combinations thereof” is intended to includeat least one of: A, B, C, AB, AC, BC, or ABC, and if order is importantin a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB.Continuing with this example, expressly included are combinations thatcontain repeats of one or more item or term, such as BB, AAA, AB, BBC,AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan willunderstand that typically there is no limit on the number of items orterms in any combination, unless otherwise apparent from the context.

All of the compositions and/or methods disclosed and claimed herein canbe made and executed without undue experimentation in light of thepresent disclosure. While the compositions and methods of this inventionhave been described in terms of preferred embodiments, it will beapparent to those of skill in the art that variations may be applied tothe compositions and/or methods and in the steps or in the sequence ofsteps of the method described herein without departing from the concept,spirit and scope of the invention. All such similar substitutes andmodifications apparent to those skilled in the art are deemed to bewithin the spirit, scope and concept of the invention as defined by theappended claims.

What is claimed is:
 1. A method of making a substantially cylindricalinsert by metal injection molding comprising the steps of: providing amold of the substantially cylindrical insert to form a substantiallycylindrical insert mold; providing a feedstock comprising a powderedmetal and a first binding agent and a second binding agent; injectionmolding the feedstock into the substantially cylindrical insert mold toform an substantially cylindrical insert having a first size; debindingthe substantially cylindrical insert to remove the first binding agent;and sintering the substantially cylindrical insert to remove the secondbinding agent and form a finished substantially cylindrical inserthaving a second size.
 2. The substantially cylindrical insert of claim1, wherein the substantially cylindrical insert comprising a top surfaceopposite a bottom surface and a substantially cylindrical couplingelement that extends from the bottom surface, a primer recess in the topsurface that extends toward the bottom surface, a primer flash holepositioned in the primer recess to extend through the bottom surface,and a flange that extends circumferentially about an outer edge of thetop surface.
 3. The substantially cylindrical insert of claim 1, whereinthe powdered metal comprises stainless steel, brass, ceramic alloys. 4.The substantially cylindrical insert of claim 1, wherein the powderedmetal comprises 102, 174, 201, 202, 300, 302, 303, 304, 308, 309, 316,316L, 316Ti, 321, 405, 408, 409, 410, 415, 416, 416R, 420, 430, 439,440, 446 or 601-665 grade stainless steel.
 5. The substantiallycylindrical insert of claim 1, wherein the substantially cylindricalinsert further comprises a flange that extends circumferentially aboutan outer edge of the top surface; and a diffuser positioned in theprimer recess comprising a diffuser flash hole aligned with the primerflash hole.
 6. The substantially cylindrical insert of claim 1, whereinthe second size is about 10 percent to about 20 percent smaller than thefirst size.
 7. An ammunition cartridge comprising: a substantiallycylindrical insert made by the process comprising providing a mold ofthe substantially cylindrical insert to form a substantially cylindricalinsert mold; providing a feedstock comprising a powdered metal and afirst binding agent and a second binding agent; injection molding thefeedstock into the substantially cylindrical insert mold to form ansubstantially cylindrical insert having a first size; debinding thesubstantially cylindrical insert to remove the first binding agent; andsintering the substantially cylindrical insert to remove the secondbinding agent and form a finished substantially cylindrical inserthaving a second size; and bonded to a substantially cylindricalpolymeric middle body comprising a substantially cylindrical polymericbullet-end and a substantially cylindrical polymeric coupling endconnected by a powder chamber, wherein the substantially cylindricalpolymeric coupling end extends over the substantially cylindricalcoupling element and covers an circumferential surface of the primerflash hole.
 8. The ammunition cartridge of claim 8, wherein thesubstantially cylindrical polymeric middle body comprise a nylonpolymer.
 9. The ammunition cartridge of claim 8, wherein thesubstantially cylindrical insert is adhesively fitted to thesubstantially cylindrical polymeric middle body.
 10. The ammunitioncartridge of claim 8, wherein the substantially cylindrical insert isadhesively fitted to the substantially cylindrical polymeric middle bodywith a curable polymer adhesive.
 11. The ammunition cartridge of claim8, wherein the substantially cylindrical insert, the substantiallycylindrical polymeric middle body or both comprises a coating to adjustthe shrinkage.
 12. The ammunition cartridge of claim 8, wherein thesubstantially cylindrical polymeric bullet-end comprises a forwardopening end having a first and a second mechanical interlock forengagement between the forward opening end and a bullet.
 13. Theammunition cartridge of claim 8, wherein the forward opening endcomprises one or more cannelures formed on an outer circumferentialsurface of the forward opening end.
 14. The ammunition cartridge ofclaim 8, wherein the forward opening end comprises one, two, three, ormore annular rings that mate with one, two, three, or more correspondingannular grooves positioned on the bullet.
 15. The ammunition cartridgeof claim 8, wherein the forward opening end is crimped so that apolymeric material flows into an annular groove of a bullet.
 16. Theammunition cartridge of claim 8, wherein a bullet is adhesively fittedto the forward opening end.
 17. The ammunition cartridge of claim 8,further comprising a diffuser positioned in the primer recess comprisinga diffuser flash hole aligned with the primer flash hole.
 18. Asubstantially cylindrical insert mold for making a substantiallycylindrical insert by metal injection molding comprising: a top surfaceopposite a bottom surface and a substantially cylindrical couplingelement that extends from the bottom surface; a primer recess in the topsurface that extends toward the bottom surface; a primer flash holepositioned in the primer recess to extend through the bottom surface;and a flange that extends circumferentially about an outer edge of thetop surface.